A 51-year-old says she's in the best shape of her life. She swapped sweaty workouts for strength training.

Growing up, Natalie Bushaw was always active. In high school, she played basketball, ran track, and became a cheerleader to ride the bus with her then-boyfriend, now-husband. By college, she got into weightliftingreaching 165 lbs and breaking the bench press record on display at the school gym.

Then, life got complicated. In 2003, Bushaw gave birth to twin boys who had health challenges and, between them, required over 30 procedures and surgeries throughout the years. Once her sons were in preschool, Bushaw wanted to start exercising more regularly.

“I was just ‘figure out who you are, Natalie, get back to the Natalie you remember who enjoyed working out, who wanted to be healthy and fit and strong and just do it,'” Bushaw, 51, told Business Insider. That year, she joined a Life Time gym near her home in Minnesota.

Since then, Bushaw has gotten a job with the gym, becoming the vice president of public relations and corporate communications for the brand. Now, she goes to the gym six times a week.

Getting into shape also got easier once Bushaw found the right treatment for her perimenopause symptoms and Hashimoto’s thyroiditisan autoimmune disease that causes the immune system to attack the thyroid gland and can lead to weight gain.

By staying consistent with her medications and finding the right workoutsBushaw said she feels “sharper and metabolically the healthiest I’ve ever been.”

Less cardio, more strength training

For years, Bushaw felt the most efficient workouts were the most demanding ones. “I wanted to get hot and sweaty and be exhausted,” she said.

Shortly after she joined Life Time, she got a personal trainer who had her do an active metabolic assessment to measure how much oxygen she’s taking in and how much carbon dioxide she’s breathing out while exercising at various intensities. Bushaw wore a fitness assessment mask as she ran on a treadmill and learned her heart rate and VO2 maxa heart measurement that can be used to gauge longevity.

The test also taught her whether she was losing fat or carbohydrates during different exercises. Some people are “sugar burners,” burning more carbohydrates than fat during workouts. Knowing which one you are can help you modify your diet and workouts to better hit your goals, such as weight loss.

Bushaw learned that she was primarily burning carbohydrates during high-intensity workouts. “So when the scale would never move, it’s because I was working out too intensely,” she said.

She changed her workout routine to focus less on fast-paced cardio and more on strength trainingknown for burning fat. She said she noticed gradual weight loss over the year, which helped her “muscles shine through.”

“It’s a mind shift because you do not burn as many calories with less intensity,” she said. “The focus isn’t the number of calories, it’s the type of calories. I needed to burn more fat calories.”

Now, she usually starts her gym sessions with 20 to 30 minutes of cardio (using the treadmill, stairmaster, elliptical, or rower). Then, she moves on to a few strength exercises for one to two body parts that day, using both barbells and 15-45 lb dumbbells.

She keeps challenging herself

Bushaw said she “progressively overloads” — a term for gradually increasing the intensity of her workouts over time.

“I think it’s really, really important that we don’t get stuck always doing the same thing or lifting the same weight because the change isn’t going to happen then,” she said.

About every six weeks, she’ll increase what she’s lifting by two to five pounds, depending on the exercise.

She also sometimes takes barre classes to switch up which muscle groups she works out. Even though barre typically uses far lighter weights than she’s used to, they feel “way heavier because you’re just using your muscles in different ways,” she said.

To get more cardio throughout the day — rather than just in one 5,000-step morning workout — she bought a walking pad for her office last year.

“I easily started hitting 10-12,000 steps and felt so much better mind, body, and soul,” she said.

She doesn’t overthink

When Bushaw first started working out again after having her twins, she had to adhere to a strict morning schedule as a working mom. She would work out from 5:23 a.m. to 6:26 a.m. every day so she could return home and get out the door before 7:30 a.m.

Sometimes, though, she wouldn’t get to bed in time to get a full night of rest. Instead of worrying about her sleep quality and talking herself out of a workout, Bushaw “would just pretend that I didn’t know how to tell time.” If she was going to bed at 11:30 p.m., she’d mentally act like she was going to bed at 10:30.

“I faked myself out, but it worked,” she said. It helped her avoid the slippery slope of missing gym sessions when plans didn’t align perfectly.

Bushaw said the key is not overthinking her workouts, such as worrying about how they fit into her children’s lives or work tasks.

“If you overthink all of the things, you’re going to get yourself stuck,” she said. “If you just make a commitment, like ‘this is what I do, this is a part of my routine,’ you can get through things a lot easier.”